This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7 119 from my application Fixing Temperature Control Method For Image Forming Apparatus filed with the Korean Industrial Property Office on the 9TH day of the month of March 2000, and there duly assigned Ser. No. 2000-11774.
1. Field of the Invention
The present invention relates generally to an image forming apparatus and processes using electrophotographic development, and in particular, to a device and process for controlling the fixing temperature in an effort to consistently form high quality images upon printable media.
2. Description of the Related Art
Electrophotographic development is widely used for an image forming apparatus like a copier, a laser beam printer, and a plain paper facsimile. The electrophotographic development is performed in the process of charging, exposure, development, transferring, and fixing in this sequential order. The results obtained from the transfer operation and the results obtained from the fixing operation vary differently as a function of environmental change. Nevertheless, the environmental conditions are classified into high temperature-high humidity, room temperature-room humidity, and low temperature-low humidity regardless of the difference between variations in the transfer performance and the fixing performance and the transfer voltage and the fixing temperature are determined according to the determined environmental condition. Since the environmental conditions are determined for the transfer performance, the fixing performance is not controlled appropriately with respect to environmental change. Room temp-room humidity ranges from 11xc2x0 C. to 31xc2x0 C. in temperature, for example. This temperature range is appropriately set for control of the transfer performance, but not for control of the fixing performance. Fixing is not reliably done at a temperature between 11xc2x0 C. and 18xc2x0 C. in the room temp-room humidity condition. Also, at a temperature between 27xc2x0 C. to 31xc2x0 C. the room temperature-room humidity condition is too high for reliable fixing and is accompanied by the phenomenon known as crinkling the paper (hereafter: crinkle).
I have noticed that typically, the fixer operation is controlled according to criteria set after considering only the changes of the transfer performance, despite the presence of differences in the variations of the transfer and fixing performances with changes in the environment ambient to the fixing operation. Consequently, it seems that fixing performance can not be effectively controlled in the presence of environmental change.
Incorporated by reference herein are U.S. Pat. No. 5,646,717 to Koichi Hiroshima et al. entitled Image forming Apparatus Having Charging Member and U.S. Pat. No. 5,895,152 to Atsushi Ide et al. entitled Fixing Device And Fixing Temperature Control Method, which describe the effects of temperature and humidity in image forming devices.
It is an object of the present invention to provide an improved image formation process and apparatus.
It is another object to provide an image formation process and apparatus for controlling the fixing temperature in an electrophotographic development type image forming apparatus.
It is still another object to provide an image formation process and apparatus using electrophotographic development, with the temperature of the fixing operation being controlled as a function of different classifications of variations in transfer performance and fixing performance.
It is yet another object to provide an image formation process and apparatus using electrophotographic development to consistently form high quality images upon printable media by controlling the temperature of the fixing operation in consideration of different variations in transfer performance and in the fixing performance as the ambient environment changes.
It is still yet another object to provide an image formation process and apparatus using electrophotographic development able to solve the problem of unreliable fixing when the fixing temperature is controlled according to a criterion that has been set with only changes in the transfer performance considered, by controlling the temperature of the fixing operation being in consideration of different variations in transfer performance and fixing performance as the ambient environment changes.
These and other objects of the present invention may be achieved by providing a fixing temperature controlling process in an image forming apparatus in order to consistently form high quality images upon printable media. The resistance of a transfer roller is detected upon request of a fixing temperature control. A determination is made of the fixing environment conditions, set according to changes in fixing performance caused by environmental change, the resistance belongs to. An optimal fixing temperature is detected for the determined fixing environment condition and the temperature of a fixer is controlled to the detected optimal fixing temperature.